Warhawk,
For starters, that's a great looking gun you have there.
You are right, it is not a "Patent" gun. The early USPFA guns were a mixture of Italian and American made parts. The transition from import/American to all American made was a gradual one and was not completed until after the company dropped the "Patent" from their name and became, as we know them now, USFA. The bulk of the USFA guns, of which yours is one, are all Amercian made.
Without digging out my old catalogs, I cannot tell you if the all blue finish was a standard catalog item on the SAA (it is standard on the current flattop, .22 Target model & the new "Cowboy" but not the basic SAA). From the photographs it appears that your gun is finished in the premium grade "Armory Blue" which would have been a special order option. It also appears, judging from the grain of the wood, that the walnut grips are of premium grade - another option.
If I had to hazard a guess, I would say that your gun was a special order item. Again, I'm just guessing here, going only on the appearance of the photographs. You might want to give USFA a call and see if they can give you a date of manufacture.
CJF